Suspensions of gelled biopolymers

ABSTRACT

Suspensions of hydrated gelled biopolymer particles obtainable by hydrating dry biopolymer particles at a temperature below T gel . Such suspensions may be used in food products such as edible spreads and ice creams or in personal care products such as skin creams and moisturizers, to impart a fatty-like character to the product.

This application claims benefit of International applicationPCT/EP94/03611, filed Nov. 2, 1994.

BACKGROUND OF THE INVENTION

(1) Field of the Invention

The present invention relates to suspensions of gelled and hydratedbiopolymer particles as well as to a process for obtaining suchsuspensions, either from dried gelling biopolymers or from dissolvedgelling biopolymers.

(2) Description of the Related Art

It is widely known that gelled biopolymer particles having a specificsize when dispersed or suspended in an aqueous medium may have usefulproperties such as imparting fat-like feel or character to products suchas edible spreads and ice creams, but also to personal care productslike skin creams and moisturizers. This is for example disclosed in EP 0355 908 (A). Such biopolymer particles are prepared from the gels whichare sheared, shredded or otherwise subjected to shear. In EP 0 501 758(A) for example it is disclosed that a preformed gel is sheared orshredded. It is also possible to simultaneously form the gel phase andapply shear to the biopolymer, as is disclosed in EP 0 355 908 (A). Aconsiderable disadvantage of these methods is that first a gel state hasto be induced by cooling a solution containing said biopolymer,whereafter the gel is sheared either during its formation or followingsetting, under controlled circumstances to yield the desired particles.

Another disadvantage of these known methods for preparing a suspensionof gelled biopolymers particles is that the preparation is carried outin a "wet" state, i.e. there is no active ingredient which can beisolated in a dry state (e.g. as a compact, dry powder or mix) whichwould be easy to store, handle, transport, sell, etcetera and which uponmixing with a (polar) liquid such as water directly yields the desiredsuspension or dispersion. The material according to EP-A-0 501 758always contains from 72 to 99.9 percent water, which makes it a bulkymaterial having considerable disadvantages on storage, transport,handling etcetera.

Suspensions of gelled hydrated biopolymers can be used as fat replacersor fat simulating material to replace fat or oil partially or completelyin food products. Another use for the suspensions is in products forpersonal care, like (skin-) moisturizers, skin creams, ointments, hairgels etcetera. For the purpose of this invention, such suspensions arehereinafter collectively referred to as a fat simulating material,although its application is not limited to food products but includespersonal care products such as skin creams, moisturizers or hair gels.

In view of the disadvantages as set out above, there is a need for aconvenient, easy to prepare fat simulating material obtainable withoutthe need to first prepare a wet gel which thereafter needs to be shearedunder controlled circumstances. Also, there is a need for such amaterial of which the active ingredient can be isolated in a dry state,thus yielding a compact, dry powder or mix which is ready to useconveniently at any time, and which, upon simple mixing with water oranother polar solvent yields a fat simulating material.

SUMMARY OF THE INVENTION

It has now been found that these objectives above can be met by asuspension of particles, which particles comprise hydrated gelledbiopolymers, which suspension is obtainable by hydrating dry particlesof said biopolymers at a temperature of below T_(gel), under thecondition that dry particles are obtained by dehydrating at atemperature of equal to or above T_(gel) a solution comprising at leastone biopolymer selected from the group consisting of agar, carrageenan,gelatin, gellan, furcelleran, alginate and (low methoxy) pectin. For thepurpose of the invention, the term "hydrating" means: mixing of dryparticles with a liquid to obtain completely wetted particles which arethereby swelled to the extent that individual particles can still beidentified (using suitable means, e.g. by microscopic observation) andthat thus no complete dissolution of the particle material takes place.Due to swelling, an increase in mean size of preferably at least afactor 2 is obtained. Hydration is preferably carried out with a polarliquid, which preferably comprises water. More preferably, the suspendedswelled particles thus obtained have a size which is between 2 and 30times larger than their size in dry state.

For most purposes, it will be preferred that 80% by weight of thesuspended biopolymer particles has a mean size below 100 μm.

Biopolymers which can be used to prepare the suspensions according tothe invention are selected from the group consisting of agar,carrageenan, gelatin, gellan, furcelleran, alginate, (low methoxy)pectin and mixtures comprising or more of these biopolymers.

DESCRIPTION OF PREFERRED EMBODIMENTS

T_(gel) is herein to be understood as the temperature at which, uponcooling, an aqueous solution of the biopolymer concerned, sets to a gel.Of course a gel can only be formed under gelling conditions. Suchgelling conditions may be different for the various biopolymersconcerned but for each of them known in the art. For example, lowmethoxy pectin requires that a certain amount of calcium ions is presentin the solution from which the gel is to be formed. Under normalconditions and using tap water, this may be the case without theaddition of extra calcium ions. However, since the amount of calciumions may influence T_(gel), it may be desired for some purposes toincrease or decrease the amount of calcium ions present in ways known inthe art such as by adding sequestrants for removing Ca²⁺. Similarly,carrageenan requires that a certain amount of metal ions like potassium,sodium and/or calcium ions are present in the aqueous solution in whichthe gel is to be achieved. Therefore, potassium-, sodium- or other metalsalt ions may be added intentionally in the form of a solution at anystage of the process of preparation of the gel.

Dry particles which can be used for the preparation of a suspensionaccording to the invention may be obtained by dehydrating at atemperature of equal to or above T_(gel) a solution comprising at leastone biopolymer selected from the group consisting of agar, carrageenan,gelatin, gellan, furcelleran, alginate and (low methoxy) pectin.Dehydration can be carried out in a number of ways known in the art,including roller drying and spray drying, but since it is needed thatthe biopolymer is obtained in a particulate form, a preferred way ofdrying is spray drying.

For specific purposes, it may be preferred to mix the dry particlescomprising the biopolymers as defined above with an additionalhydrocolloid (like e.g. xanthan, guar gum, locust bean gum or modifiedcelluloses) and/or a starch-derivative (such as maltodextrin). This canbe done by either simple mixing of the dry ingredients or by co-drying(e.g. co-spray-drying) a solution of the biopolymers with the additionalcompound.

An integrated process for the preparation of a suspension according tothe invention, starting from a solution of at least one (gellable)biopolymer selected from the group consisting of agar, carrageenan(kappa- and iota-), gelatin, gellan, furcelleran, alginate and (lowmethoxy) pectin) may comprise the following steps:

a. drying the solution at a temperature of at least T_(gel), followed byor simultaneously with

b. particulation of the dry material, followed by

c. hydrating the obtained particles with a polar liquid at a temperaturelower than T_(gel).

Preferably, step a. and b. are carried out simultaneously, which can beachieved by e.g. spray drying the solution comprising the biopolymer.

For preparing a fat simulating material any suitable biopolymer may beused depending on the specific application, as long as the biopolymersused are capable of forming a gel. Examples of such biopolymers are:carrageenan, gelatin, gellan, furcelleran, alginate, pectin or mixturesthereof. The specific application and the type of biopolymer may alsodetermine the amount of particles needed to achieve the desiredproperties of a fat simulating material. Amounts may range up to 15% (bydry weight) of particles, calculated on the total amount of suspension.

Depending on the end-use of the suspensions according to the inventionthey may further comprise components like flavours, fragrances, colours,vitamins, salts, sugars, sugar alcohols, UV-absorbers, emulsifiers orother adjuncts.

The suspensions according to the invention may be used in a food productor personal care product, for example in order to partially orcompletely replace fat of animal or vegetable origin which would benormally present therein.

The suspensions according to the invention can be may be used to replaceall or a portion of the fat, oil or cream in food products like icecream, yoghurt, salad dressings, mayonnaise, cream, cream cheeses, othercheeses, sour cream, sauces, icings, whipped toppings, frozenconfections, milk, coffee whiteners and spreads. The suspensionaccording to the invention can also be used in personal care products.

The invention is illustrated by the following examples but is in no waylimited thereto.

EXAMPLE 1

By co-spray drying at a temperature T above T_(gel) three samples ofagar containing particles were prepared. The obtained particlescontained the following ingredients:

    ______________________________________                                        no:         composition:       ratio                                          ______________________________________                                        (weight):                                                                     1           agar + maltodextrin                                                                              1:4                                            2           agar + maltodextrin + xanthan                                                                    1:3:0.05                                       3           agar + maltodextrin + xanthan                                                                    1:3:0.1                                        ______________________________________                                         The agar used in all experiments was: Biogar (ex Quest International). Th     maltodextrin used in all experiments was: Paselli SA2 (ex Avebe). The         xanthan used in all experiments was: Jungbunzlauer foodgrade xanthan.    

A conventional spray-drier was used having the following diameters:total chamber height is 1.8 meters, the top cylindrical section having adiameter of 1.3 meters and a height of 1.0 meters with the conicalsection being at an angle of 60° for 0.8 meters from the cylinder. Inlettemperature of the spray-drier was 190° C., outlet temperature about 90°C. Feed rate was 9 1. per hour. The agar concentration was about 3.5% byweight and does not include the other ingredients. A spinning disc-typeatomizer was used for particulation.

The particle sizes of the dried powders were obtained using a Quantimet970 Image Analyser. The powders were spread over a microscope slidewhich was sonicated in order to obtain, as best as possible, discreteparticles. It should be noted that the image analysis routine in theQuantimet ignores large, irregular shaped particles in determiningparticles sizes, i.e. particles that have clumped together. The resultsof the obtained particle size measurements of the dry particles are setout in table 1.

                  TABLE 1                                                         ______________________________________                                        particle size distribution dry agar particles                                 (cumulative mean diameters)                                                   upper limit                                                                   (μm)    no. 1        no. 2   no. 3                                         ______________________________________                                        5.0        22.28        29.57   29.25                                         7.5        59.69        68.78   65.73                                         10.0       82.28        87.85   81.81                                         12.5       92.35        95.46   90.68                                         15.0       96.79        98.20   94.50                                         17.5       98.70        99.26   97.27                                         20.0       99.60        99.63   98.67                                         22.5       99.84        99.83   99.48                                         25.0       99.98        99.88   99.86                                         27.5       100.00       100.00  100.00                                        ______________________________________                                    

EXAMPLE 2

The particles were dispersed or suspended in water in the followingmanner:

1. dried agar powder as obtained by spray drying according to theprevious example (1 g) was gradually dispersed in cold water (100 ml)using an Ultraturrax T25 Homogeniser with a 16N probe (speed setting8000 rpm).

2. Once the powder was fully dispersed the homogenisation speed wasincreased to 24000 rpm for 2-3 minutes.

3. The thus obtained particles were left to equilibrate for at least 1hour before being measured. The obtained mix appeared to be translucent.

Image analysis on the resulting suspensions was not possible using theQuantimet, due to the similarity between the particle and solventrefractive indices. In order to determine the particle size of thedispersed particles a Malvern Mastersizer X was employed. The resultsare set out in table 2.

                  TABLE 2                                                         ______________________________________                                        particle size distribution suspended agar                                     particles (cumulative mean diameters)                                         upper limit                                                                   (μm)    no. 1        no. 2   no. 3                                         ______________________________________                                        5.24       0.03         0.0     0.0                                           7.78       0.33         0.08    0.11                                          11.55      1.69         1.51    1.42                                          17.15      9.82         11.16   9.93                                          25.46      31.57        34.03   30.91                                         37.79      65.44        62.80   59.11                                         56.09      90.85        84.16   81.32                                         83.26      97.79        93.24   91.14                                         123.59     97.81        96.22   94.66                                         183.44     98.14        98.27   97.45                                         272.31     99.37        99.69   99.49                                         404.21     100.00       100.00  100.00                                        ______________________________________                                    

EXAMPLE 3

Kappa-carrageenan particles were dispersed or suspended in water in thefollowing manner:

1. dried kappa-carrageenan (ex Quest International, tradename Deltagel)powder as obtained by spray drying similarly to example 1 (1 g) wasgradually dispersed in cold water (100 ml) containing 0.015 M KCl usingan Ultraturrax T25 Homogeniser with a 16N probe (speed setting 8000rpm).

2. Once the powder was fully dispersed the homogenisation speed wasincreased to 24000 rpm for 2-3 minutes.

3. The thus obtained particles were left to equilibrate for at least 1hour before being measured. The obtained mix appeared to be translucent.

In order to determine the particle size of the dispersed particles aMalvern Mastersizer X was employed. The results are set out in table 3.

                  TABLE 3                                                         ______________________________________                                        particle size distribution suspended carrageenan                              particles (cumulative mean diameters)                                                Upper limit                                                                   μm   no. 4                                                          ______________________________________                                               15.58   0.32                                                                  22.97   8.04                                                                  33.87   35.08                                                                 49.95   67.54                                                                 73.66   89.47                                                                 108.61  97.70                                                                 160.17  98.84                                                                 286.82  98.84                                                                 513.61  98.91                                                                 1356.26 100.00                                                         ______________________________________                                    

EXAMPLE 4

A moisturizing personal care product was prepared using the followingformulation (all percentages by dry weight):

2.5% spray dried kappa-carrageenan (similar to the carrageenan obtainedin example 3)

3% glycerol

0.06% colouring agent

0.1% flavour

0.1% preservative (sodium methylbenzoate)

0.11% potassium chloride

remainder water

i) All ingredients, excluding the carrageenan, were dissolved in thewater at room temperature.

ii) The carrageenan was gradually added to the resulting liquid andsuspended using an T25 ultraturrax with a 18G probe, on a low speedsetting.

iii) Once the suspension is complete, it was mixed at a higher shearsetting for about 2 minutes to achieve a smooth texture.

The resulting product was a pourable, smooth composition with afatty-like appearance suitable for topical application to the skin.

EXAMPLE 5

A dressing type product was prepared using the following recipe (allpercentages based on dry weight):

6% co-spray dried agar/maltodextrin/xanthan mixture (ratio 1:3:0.05respectively) maltodextrin being a 2DE maltodextrin (Paselli SA2, exAvebe) xanthan being a food-grade xanthan ex Jungbunzlauer

4% sucrose

2.2% salt

2% flavours and spices

0.13% potassium sorbate (preservative)

remainder water

i) all ingredients were dissolved at room temperature, excluding theagar-containing mixture

ii) the solution was titrated to pH 3.8 with wine vinegar

iii) the agar-containing mixture was slowly added to the aqueouscomposition under moderate shear using an ultraturrax T25 with 18G probeon a medium setting.

iv) once addition was complete, shear was increased to high setting forabout 2 minutes.

A product was obtained which had a rheology and texture very muchsimilar to conventional fat containing dressing type products.Furthermore, the product obtained showed good stability.

EXAMPLE 6

A similar product as in example 5 was prepared by using 7.5% co-spraydried agar/maltodextrin (ratio 1:4 respectively)

We claim:
 1. A suspension of particles which comprise hydrated gelledbiopolymer, said suspension being obtained by hydrating at a temperaturebelow T_(gel) dry particles of said biopolymer, said particlesthemselves being obtained by dehydrating a solution comprising thebiopolymer at a temperature of above T_(gel), the biopolymer beingselected from the group consisting of agar, carrageenan, gelatin,gellan, furcelleran, alginate, (low methoxy) pectin and mixturesthereof.
 2. A suspension according to claim 1 wherein the biopolymerparticles have a size which is between 2 and 30 times larger than intheir unhydrated state.
 3. A suspension according to claim 2 wherein atleast 80% by weight of the hydrated biopolymer particles has a mean sizebelow 100 μm.
 4. A suspension according to claim 3 wherein saidsuspension further comprises at least one member of the group consistingof a hydrocolloid and a starch based material.
 5. A suspension accordingto claim 4 wherein the starch based material comprises maltodextrin. 6.A suspension according to claim 5 wherein the hydrocolloid comprisesxanthan, guar gum, locust bean gum or modified celluloses.
 7. Asuspension according to claim 1 wherein further comprises flavours,fragrances, colours, vitamins, salts, sugars, sugar alcohols,emulsifiers or other water soluble adjuncts.
 8. A food product orpersonal care product comprising a suspension according to claim
 1. 9. Afood product according to claim 8 which is at least partially orcompletely free of animal or vegetable fat.
 10. A process for thepreparation of a suspension of particles which comprise hydrated gelledbiopolymer, said process comprising mixing dry particles of a biopolymercapable of forming a gel selected from the group consisting of agar,carrageenan, gelatin, gellan, furcelleran, alginate, (low methoxy)pectin and mixtures thereof with a liquid at a temperature lower thanT_(gel) of said biopolymer, said dry particles being obtained bydehydrating a solution comprising said biopolymer at a temperature aboveT_(gel).
 11. A process according to claim 10 wherein the liquidcomprises water.